1. Field of the Invention
The present invention relates to catalyst components, catalyst systems, olefin polymerization, polymer compositions, and to articles made from such polymer compositions. More particularly the present invention relates to catalysts having C1, C2 or CS symmetry.
2. Description of the Related Art
As is well known, various processes and catalysts exist for the production of polyolefins. Traditional Ziegler-Natta catalyst systems utilize a transition metal compound cocatalyzed by an aluminum alkyl.
In the 1980's, metallocene catalysts for olefin polymerization were commercialized that included a metallocene and an aluminum alkyl component, with a transition metal compound having two or more cyclopentadienyl (Cp) ring ligands. Accordingly, titanocenes, zirconocenes and hafnocenes have all been utilized as the transition metal component in such a metallocene containing catalyst systems for the production of polyolefins. Metallocene catalysts can be cocatalyzed with an alumoxane, rather than an aluminum alkyl, to provide a metallocene catalyst system of high activity for the production of polyolefins.
In addition to Ziegler-Natta catalysts and metallocene catalysts, a number of “non-metallocene” type catalysts have been suggested for the polymerization of olefins. Specifically, for example, in The Search for New-Generation Olefin Polymerization Catalysts: Life Beyond Metallocenes, Angew. Chem. Int. Ed. 1999, 38, 428-447, Britovsek et al. review a number of olefin catalyst systems, including: Group 3 metal catalysts such as scandium and yttrium complexes; Rare Earth Metal catalysts such as lanthamide and actinide-based catalysts stabilized with substituted cyclopentadienyl ligands; cationic Group 4 metal complexes including carbon-based ligands (such as alkyl ligands, allyl ligands, Cp analogues), including nitrogen-based ligands (such as amide ligands either along or in combination with other ligands, amidinate ligands either alone or in combination with other ligands, and β-diketimate ligands), and including oxygen-based ligands (such as alkoxide ligands either alone or in combination with other ligands, bisalkoxides with additional donors); neutral Group 4 metal complexes; Group 5 metal catalysts; Group 6 metal catalysts; Group 8 metal catalysts; Group 9 metal catalysts; Group 10 metal catalysts; Group 13 metal catalysts.
Additionally, in Iron and Cobalt Ethylene Polymerization Catalysts Bearing 2,6-Bis(Imino)Pyridyl Ligands; Synthesis, Structures, and Polymerization Studies, J. Am. Chem. Soc. 1999, 121, 8728-8740, Britovsek et al. disclose certain iron and cobalt catalysts for the polymerization of ethylene.
WO 98/30612, published on Jul. 16, 1998, discloses selected iron complexes of 2,6-pyridinecarboxaldehydebis(imines) and 2,6-diacyclpyridinebis(imines) as catalysts for the polymerization of propylene. WO 99/12981, published on Mar. 18, 1999, discloses catalyst complexes having a bridge comprising heteroatoms bridging R groups R5 and R7, with these complexes taught as being useful “especially for polymerizing ethylene alone or for copolymerizing ethylene with higher 1-olefins” (page 2, lines 28-29). The bridged R groups R5 and R7 are independently selected from hydrogen, halogen, and hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted heterohydrocarbyl. There is no teaching or suggestion to make a chiral complex suitable for producing high tacticity, crystallinity polypropylene.
The following patents disclose bridged metallocene catalyst systems: U.S. Pat. No. 5,145,819, issued Sep. 8, 1992 to Winter et al.; U.S. Pat. No. 5,158,920, issued Oct. 27, 1992 to Razavi; U.S. Pat. No. 5,243,001, issued Sep. 7, 1993 to Winter et al.; U.S. Pat. No. 6,002,033, issued Dec. 14, 1999 to Razavi et al.; U.S. Pat. No. 6,066,588, issued May 23, 2000, to Razavi et al.; U.S. Pat. No. 6,177,529 B1, issued Jan. 23, 2001, to Razavi et al.; U.S. Pat. No. 6,194,343 B1, issued Feb. 27, 2001 to Collins et al.; U.S. Pat. No. 6,211,110 B1, issued Apr. 3, 2001 to Santi et al.; and U.S. Pat. No. 6,268,518 B1, issued Jul. 31, 2001 to Resconi et al.
However, in spite of the above advancements, there still exists a need in the art for catalyst compositions, methods of making such compositions, methods of polymerization using such compositions, to polymer compositions, and to articles made from such polymer compositions.